Over weight ttc

So my doc told me I'm over weight an its clear that I know this she said it could be a reason behind my period being late. This first time ever she also mentioned that if I loose 30 pounds then I would have a better chance at concieving, not to mention that 20lbs total is my damn boobs literally I got them weighed before smh.. missed periods mean no ovulation that could be because of weight too. But why is it that I seen women over 300 lbs have kids an my weights a issue. Smh. Just don't make sense.